Zinc-Rich Coatings for Aluminum in Seawater

Abstract

Abstract : Aluminum 6061-T6 coated test panels were prepared for exposure in the harbor water at Port Hueneme, California. Surface preparation of most of the panels was by a light sandblast before application of selected coatings; but one series was merely washed clean with water and then with mineral spirits, and another was treated with Alodine 1200S before the coatings were applied. Zinc- rich primers of various types were used, topcoated with epoxy vinyl or coal-tar epoxy systems. After three years of exposure coatings over the Alodine 1200S gave good to excellent protection comparable to that over the zinc inorganic silicates. The topcoated zinc-rich organic primers were slightly inferior to the zinc inorganic silicates. Several coating systems gave excellent protection during the three years of harbor exposure and indicated a protective potential for several years more.